Push button switches comprising curved deformable contact elements, such as dome-shaped contact elements, are used in a number of applications where it is desired to establish electrical connection between one set of terminal points to another set of terminal points by deformation of the deformable contact element. The terminal points may typically be arranged along the edge of the deformable contact element and centrally below the concave surface thereof so that contact is obtained by excering a pressure on the deformable contact element. Such a switch may e.g. be used in equipment that is to run only when a safety button is being constantly pressed, or in equipment where a signal is to be generated when a button is pressed. Such a signal may e.g. be an audio signal used to get attention, or it may be a signal adapted to trigger the start of another set of events.
For some applications, such as for safety buttons as described above, there is a risk of an erroneous continued registration of the button being pressed even after the user of the equipment has stopped pressing the button. As an option in such appliances, one could run a check on both of the outputs of a normally open normally closed switch to assess whether the button is pressed or not.
Hence, an improved push button switch would be advantageous, and in particular a more reliable push button switch would be advantageous.